When burning heavy oil, such as bunker C or crude, which is difficult to ignite, an ignitor burner is generally used today which uses natural gas or No. 2 oil as the ignitor fuel. The increasing cost and decreasing availability of natural gas and No. 2 fuel oil has recently become a subject of growing concern. Thus it is desirable to reliably light off the heavy oil directly by means of a high energy spark ignitor, eliminating the need for natural gas or No. 2 fuel oil ignitors.
Even when an ignitor burner is used for lighting heavy oil main burners, it is important that the main burner fuel be ignited every time, with a stable main flame being established.